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La importancia de los medios de comunicación hoy en día, y su papel como creadores de opinión pública es tal, que se han convertido en fuente importante de donde extraer datos a la hora de iniciar una investigación. Nadie como ellos ofrece tal cantidad de información, periódica y puntual, sobre personas, actividades empresariales y sociales, hechos, etc. En este sentido, el volumen de información – diaria, semanal, mensual – que se ofrece es tan grande que el acceso a la misma supone una primera barrera para quien quiera iniciar su investigación. Por otro lado, no hay que olvidar la presencia de otros elementos (imparcialidad, falta deliberada de verdad informativa, manipulación) que ciertos medios imprimen a sus productos. Errores, o al menos, datos sesgados, son un segundo escollo importante que debe sortear el investigador.

International audience; X-ray diffraction and dielectric measurements show the existence of three phases in the PbZr1-x(Fe1/8Nb1/2)xO3 solid solutions...

A portable underwater source-receiver system, supporting equipment, and digital computer software have been developed to determine near-surface sound speed and attenuation at harmonic frequencies from 5 to 95 kHz simultaneously, and in-situ from a ship. These data have yielded values of bubble densities as a function of bubble radius from 40 to 1000 microns, depth to 15.2 meters, time of day, varying oceanographic conditions and environmental parameters for two days in November in Monterey Bay. http://archive.org/details/soundspeeddisper1094517244 Lieutenant, United States Navy Lieutenant, United States Navy Approved for public release; distribution is unlimited.

A great deal has been written on the part which birds play in the dispersal of freshwater fauna. This article summarises literature on the dispersal of aquatic animals by birds and aquatic insects. Translated from German into English

The statistics of the fluctuations of the is-situ speed of sound in the upper ocean have been studied by analyzing the instantaneous phase difference of the output of two hydrophones separated by one meter for sounds of frequency 15 to 151 kHz. The experiment was conducted at 11 ft. in water depth of 60 ft. in low sea states at night. Comparison of the speed calculated from the time averaged phase difference, with the speed given by velocimeter or empirical relations, yielded differential speeds which deviate by 1 m/sec to 8 m/sec from the accepted values, for frequencies less than 100 kHz. Correlation and spectral analysis of the sound phase and ocean height fluctuations has shown the close relation between these two parameters. There is strong evidence of the presence and importance of bubbles in all the results, particularly of a large population resonant in the frequency range 56.3 to 71.1 kHz (radius 50 to 60 microns). Evidence is presented to suggest that bubbles appear at the surface during internal wave activity at lower depths and that for sound frequencies near the bubble resonances the sound phase is strongly modulate by, and in phase with, the ocean wave height. http://archive.org/details/statisticalstudy1094516369 Lieutenant Commander, United States Navy Approved for public release; distribution is unlimited.

The study of soil erodibility has become of paramount interest in the last few decades. The effects of soil erosion are serious and extensive and affect nearly all people.

Fatigue and dispersion strengthening are reviewed generally. Experiments are described in which thin film transmission electron microscopy, as well as optical and electron fractography were employed to elucidate the mechanism of fatigue failure in dispersion strengthened nickel. It was found that whereas fatigue crack initiation occurs as in conventional materials, the propagation of both fatigue and tensile cracks is abnormal. The material fails in shear wherever possible although this is prevented where triaxial tensile stresses exist. Particle-matrix detachment does not occur during either tensile or fatigue stressing. Thesis Master of Science (MS)

A theoretical treatment of diffusion as function of turbulence, by working out the dispersion of small particles in turbulent fluid. The method of Kolmogoroff is used to decribe the movement in a statistical ways

This short paper summarises findings of experiments that were carried out using copepod eggs taken from guts of Coregonus which breeds in various Ural lakes. The study showed that copepod eggs can pass through the gut of Coregonus unharmed. Translated from Russian into English

Three cluster analysis programs were used to group the same 64 individuals, generated so as to represent eight populations of eight individuals each. Each individual had quantitative values for seven attributes. All eight populations shared a common attribute variance-covariance matrix. The first program, from F. J. Rohlf's MINT package, implemented single linkage. Correlation was used as the basis for similarity. The results were not satisfactory, and the further use of correlation is in question. The second program, MDISP, bases similarity on Euclidean distance. It was found to give excellent results, in that it clustered individuals into the exact populations from which they were generated. It is the recommended program of the three used here. The last program, MINFO, uses similarity based on mutual information. It also gave very satisfactory results, but, due to visualization reasons, it was found to be less favorable than the MDISP program.

The passive spread of a high percentage of freshwater organisms is one of the most important requirements in short-lived and insular communities for species to attai n and survive - and consequently to balance the lack of a topographical continuity of most inland waters. Unfortunately hardly anything is known about the amounts of seed material typical for any lake into which it is carried. The causes of passive dissemination - wind, water and animals as well as man - are confirmed by many examples. It has been assumed now for at least a hundered years that , among animals, birds play a prominent role, although also disappointingly few facts are at hand. The passage and spread through birds' intestines has up to now been supported only by some limited data. This paper reports on experimental research where the eggs of Daphnia magna, Triops cancriformis, Artemia salina, Diaptomus spinosus and Cypris pubera were introduced by means of gelatine capsules into the oesophagus of a drake. The bird's excrements were inspected under a microscope for eggs and resting stages, and these were transferred into corresponding cultures. Translated from German into English